package com.gzsxy.JUC.forkjoin;

import org.omg.CORBA.PUBLIC_MEMBER;

import java.util.concurrent.RecursiveTask;

/**
 * 求和计算的任务
 * ForkJoin  、  stream并行流
 * 1.  forkjoinpool 通过它来执行
 * 2. 计算任务forkjoinpool.execute(Forkjointask task)
 * 3.计算类要继承RecursiveTask
 */
public class ForkJoinDemo extends RecursiveTask<Long> {

    private Long start;  //1
    private Long end; //196546545655

    //临界值
    private Long temp = 10000L;

    public ForkJoinDemo(Long start, Long end) {
        this.start = start;
        this.end = end;
    }

    public void test() {

    }

    //计算方法
    @Override
    protected Long compute() {
        if ((end - start) < temp) {
            //分支合并计算
            Long sum = 0L;
            for (Long i = start; i <= end; i++) {
                sum += i;
            }
            return sum;
        } else {  //forkjoin

            long middle = (start + end) / 2; //中间值
            ForkJoinDemo task1 = new ForkJoinDemo(start, middle);
            task1.fork(); //拆分任务，把任务压入线程队列
            ForkJoinDemo task2 = new ForkJoinDemo(middle + 1, end);
            task2.fork(); //拆分任务，把任务压入线程队列
            return task1.join() + task2.join();

        }
    }
}
